Can dictionaries be stored in globalDict?
The list is only an example of types -


  Python built in types such as int/string/bool/float/tuples/lists can be saved, 


while it does not give a complete list of built-in types, a dictionary is a built-in python type so does belong to that list of types. While an int and float may be simpler types, a list or tuple would be equal to a dictionary in this context.


  GameObjects, Actuators etc will not work as expected.


This indicates the types defined by blender, most of which are not fully implemented the way that the python built-in types are, will not work as expected.

As the first line states can be saved which also implies being loaded back between games, I would expect the exact criteria to be types that are picklable, which would also mean that the items in the dictionary must also be built-in types, not blender types. Of course if you aren't actually saving the globalDict between games and just want to use it during game play then you should find these restrictions to be irrelevant.